PAC Machine Edition Alarm Window - what trigger clear all??

[AlexTuzi]

Hello everyody,

So, I am working in this projetc that was abandoned by the integrator. It a PAC Machine Edition PLC and HMI with LV7000 GE drives.
I have a screen where I have an Alarm Window which is set up to show all inverter faults. The problem is that somethin is triggering a Clear All command and all alarms is vanishing when main power is disconeected, even tough PLC and HMI are still on because they are on a no break circuit.

This is quite annoying, because the LOTO procedure here is on the main power disconnector.

Can anyone shed a light?

thanks.

 

[keithlyding]

I don't know the PLC, but I can think of a few different things I might try:
1. Check if HMI has an alarm history screen, instead of just active alarms--the alarms should then able to be viewed with a timestamp upon re-energizing power
2. Use a historian like ignition and historize the alarm tags
3. Add a latch or counter to each rung after the alarm output (in the PLC) to "catch" which alarms came in. Depending on the PLC, these should "remember" their last status before power was shut off.
4. Put your 24vdc power supply on the top side of the disconnect, thus preventing loss of power to your PLC and HMI. I personally hate losing my 24v when the main disconnect is cycled.

 

[Steve Bailey]

I'm assuming the HMI is a target in the Machine Edition project and that the faults are defined in the HMI target. There could be a script triggered by something that happens when the main power is disconnected. There will be a list of scripts in the project navigator, but there could also be screen-based scripts. Expand the alarm screen in the project navigator to see if there are screen scripts.

 

[AlexTuzi]

Nailed it! It was exactly a script triggered by a bit that changed state when the power goes off.
Thanks!